Airplane wing spar joint



July 22, 1947. A UTSCH AIRPLANE WING SPAR JOINT Filed oct. 8, 194s 2sheets-sheet 1 July 22, 1947. A. UTsCH AIRPLANE WING SPAR JOINT FiledOct. 8, 1943 2 Sheets-Sheet 2 Patented July 22, 1947 AIRPLANE WING SPARJOINT Albert Utsch, Normandy, Mo., assgnor to Mc Donnell AircraftCorporation, St. Louis, Mo., a corporation of Maryland ApplicationOctober 8, 1943, Serial No. 505,477

(C1. 28d-F9) 12 Claims.

This invention relates principally to joints for connecting the spars ofthe detachable outboard section of an airplane wing to the inboardsection thereof. The invention has for its principal object to devise asimple and economical, strong and rigid light-weight spar joint that canbe readily adjusted to compensate for misalinement and variations in theshape and dimensions of the cooperating parts due to damage thereto andadverse tolerances; that can be quickly and easily connected anddisconnected in the eld without factory equipment; and that willincrease the shear resistance of the joint. The invention consists inthe airplane wing spar joint and in the construction, combinations andarrangements of parts hereinafter described and claimed.

In the accompanying drawings, which form part of this specification andwherein like symbols refer to like parts wherever they occur,

Fig. 1 is a plan view of a portion of an airplane wing provided withwing spar joints embodying my invention.

Fig. 2 is an enlarged fragmentary plan View of the connected endportions of the inboard and outboard wing spars, the upper connectionbeing shown partly in horizontal section,

Fig. 3 is a view similar to Fig. 2 showing the lower connection partlyin horizontal section,

Fig. 4 is a fragmentary side elevational View of the connected endportions of the inboard and outboard wing spars,

Fig. 5 is a vertical sectional View on the line 5 5 in Fig. 3,

Fig 6 is a View similar to Fig. 5, showing the operating arm on theeccentric bushing and the nut on the outboard bolt,

Fig. 7 is a perspective View of one of the eccentric bushings,

Fig. 8 is a perspective view of the shear pin element of the lowermostconnection; and

Fig. 9 is a perspective View of one of the adjusting arms for theeccentric bushings.

In the accompanying drawings, my invention is shown embodied in anairplane wing comprising an inboard section I and an outboard section 2that is detachable from said inboard section for replacement and forconvenience in storing and shipping. The inboard wing section I isprovided with spars 4 and the outboard section 2 is provided with spars3 that are rigidly connected in alining relation to the correspondinginboard wing spars by a joint comprising upper and lower connections Aand B, respectively, the same reference characters designating similarparts of each of said connections.

Each of the connections A and B comprises two splice bars or links 5that span the abutting ends of the inboard and outboard wing spars andare rigidly secured flatwise to opposite sides of corresponding cornerportions thereof by horizontal inboard and outboard bolts 6 and 1,respectively. The inboard bolt 6 extends through registering holes inthe inboard wing spar 4 and splice bars 5 and is provided at each endwith a castellated nut 8 that is locked to said bolt preferably by meansof a cotter pin 9. The nut 8 bears against a washer I0 that seatsagainst the outer end of an eccentric bushing I I that is sleeved on theinboard bolt 6 and is rotatably7 mounted in the cylindrical inboard bolthole I2 in the adjacent splice bar 5. The eccentric bushing II has anoutstanding circumferential flange I3 at the outer end thereof that islocated between the washer I 0 and the outer side face of the splice bar5. l

An operating arm I4 has an opening I5 in the hub portion thereof that tsthe flanged outer end I3 of the eccentric bushing II. The operating armI4 is held in place on the end flange I3 of the eccentric bushing II bymeans of the washer I0; and said end flange is provided with a series ofne peripheral serrations I6 that interlock with a similar series ofserrations I'I in the opening I5 in the hub of said operating arm,whereby said bushing may be rotated by said arm in the inboard bolt holeI2 in the splice bar 5 relative to the inboard bolt 6 and said operatingarm may be angularly adjusted with relation to said bushing. Theoperating arm I4 is locked to the splice bar in the desired position ofrotary adjustment by means of a cap screw I8 that extends through thefree outer end of said arm and is threaded into said splice bar 5.

The outboard bolt 1 of each of the connections A and B extends throughregistering openings provide therefor in the outboard wing spar 3 andthe splice bars `5 on vopposite sides thereof and is provided at eachend with a castellated nut I9 that is locked to said bolt by means of acotter pin 25. The nut bears against e, washer 2l that seats against theouter end of a con- Vex spherical bushing 22 that is sleeved on theoutboard bolt 'I and is supported in the concave spherical surfaceprovided therefor in the outboard bolt opening 23 in the link 5. The capscrew I8, which locks the bushing adjusting arm I4 to the splice bar 5,is locked in tightened position by means of a wire loop 24 that extendsthrough the head of said cap screw and the outer end of the outboardbolt 1 and has its ends twisted together.

As shown in the drawings, one of the connections A and B, preferably thelowerrnost connection B, is provided with means for increasing theshearing resistance thereof. This shear resisting means preferablycomprises a hollow cylindrical shear pin 25 that seats within opposedtransverse grooves 26 provided therefor in the opposing end faces of theinboard and outboard wing spars opposite the splice bars 5 and termtjacent end thrust flange 21 of the shear pin 251 The hereinbeforedescribed wing spar joint ^con`- struction has numerous importantadvantages. The two connections A andjjB forming thecomvplete wing sparjoint are 'each separately "assembled, adjusted and disassembled in thesari'le manner and permit the outboard wing spars'iY to be quickly andeasily attached to and detached from the inboard wing spars 4. bushingsl I atoppositeends of the inboard bolts Kif-"areindependently'adjustable by'inean'sof their operating 14Std take up auplay' inthe ma nlgfpartfsr 'duef'to'jdainage thereto o r large ma"facturing tolerancesl and tov'properly tensiont ea'chsplice b'a'rf'v`so Yasto'pre-'s'tressA the joint and thus' avoid unnecessary motion ofthe wingY tips in landing, takeo'ffs and maneuvers'. The sphericalbushings 22 at'opposit'e ends yof the'outboardfbolts 'I accommodate anymisalinemerit of Vthe connected'wingspar ends; andthe shear' pin 2'5 inthe lower'connection B prevents relative verticalrnove'm'ent of theconnected wing spais and thus 'takes'`v the vertical shear load whilethe end flanges of said pin serve to prevent vthe same from slippingendwise from the lnotches in the opposing'ends ofjsaid wing'spars duringthe operationjofassembling,the joint." 'Repair outboardvving sectionsmayb'e readily "secured to thi'ginal inboar'd wing ,sections and the:spar j ints'prop'erly tensioned'in the eld withoutfactor'jf' equipmentdespite llack'of t' of 'the repair section-with' the original section.v'The splice'bar can 'be placed lunder 'equal tension turningthe'foperating arms 'for` the e'ccentricbushing, after which thearmsfare detachedfromthebush; in'gsan'd replaced in position for'locking tothe splice Abars by means o'f the lock screws I8.

`Obviously the' joint construction hereinbefore described admits lofnconsiderable modification without 'departing from invention and isappiibabietpsectional'airroiiscfvari'oustypes.

l. An airfoil spar joint construction comprisingctwo spars disposed'inend'cto end relation, splice bars disposed on opposite sides of saidspars andspanning the adjacent ends thereof, 'and separate connectionsbetween said rsplice bars and the "respective spars, onel of saidvconnections including separate means cooperating with each of saidsplice 4bars for'taking'up'play in said joint and for separately"tensioning each of said splice bars.

`2. -An airfoil sparV joint construction comprislng two spar's disposedin end to end relation, splice barsdi'sposedon opposite sides of' saidspars an`dspanning the adjacent ends thereof, and vseparate connectionsbetween said splice bars and the'respective'spars, one ofsaid'connections including means for accommodating misalinement ofthespars and the other of said connections including means forseparately'adjusting each of saidvsplice bars relative to said 'spars totake up I )lay'` in saidv 'spar` joint and'to tension said'splice bars.f

`3. Anairfoil spar joint construction comprising two" spars"di `sposed'end' to en d relation, splice bars disposed. on opposite" sides of saidspars and spanning the' adjacent ends thereof, said vspars havingopposedtransverse grooves in said ends thereof', and' separateconnections be- The-'eccentric tween said splice bars and the respectivespars, one ofvsaid connectionsincluding'rneans for acoornrn'odatingnisalinementy of the* spars and the other ofi saidconnections including 4means for separately adjusting each of saidsplice bars relative to said spars to take up play in said spar jointand to tension said splice bars, and a shear pin seating in said opposedgrooves in said ends of said spars and having flanges overlapping theside faces thereof.

4. An airplane wing spar joint construction comprising two wing sparsdisposed in end to end relation, splice bars disposed on opposite sidesof vsaid wing spars and spanning the adjacent ends thereof, andreleasable connections between each of said splice bars and therespective'spars, the connection'between each splice bar'ando'ne of said-spars' being adjnstablefor taking up play in said joint and fortensioning said splice bar,l and the connection between'each splice barand the other of said'spars being'selfadjustable to accommodatemisalinement of said Spam..

5. Avn airplane wing spar joint construction coinprisinginboard andoutboard wing spars dis"- posed in end to end relation, splice barsdisposed on' oppositev sides of said wing-spars and spanning the'adjacent ends thereof, 'said'i'nboard spar and the inboa'rd lendsofsaid splice bars having reg'- is'tering' v'openings therein, a boltextending through said registeringopenings, eccentric bushings sleevedon saidbolt'f androtatable in the openings V`provided' therefor "in said'splice bars, and means associated with said eccentric bushings forrotating them relative to said bolt and splice bars totake up play insaid joint.

6. An airplane wing spar joint construction comprising inboardandoutboard wing' spars disposed in end to end relation, splice barsseating against opposite 'sides of said wing spars" and spanning theadjacent ends thereof,`saidinboard spar and the inboa'rd ends of saidsplice bars having'r'egistering openings therein, afb'olt exi tendingthrough said registering openings; eccentric bushings sleeved onsai'd'bolt and'rotatable in the openings in said splice bars, and meansassoc'ziatedv with saidecce'ntric bushings for rotating them relativelto said bolt and'splice bars to take up play in'said joint, saidmeanscomprising 'an arm xedtov eachof said bu'she ings. A

"7. 'An airplane wing spar joint construction comprising inboard andoutboard wing spars disposed' in end to end relation, splice" bars'disposed on Aopposite sides of said Wing' spars and spanningtheadjacent ends thereof, `said adjaf cent ends ofA saidwing'spars havingopenings therein andw'said'splice bars' having openings inthe'endshthereof registering Withthe respective wing sp'ar openingsg'theopenings inthe outboard endsof said splice bars'having'spherical'su'rfaces a 'bolteXtending through the registeringopenings'in said inboard wing spar andthe inboard ends of said splicebars, eccentric bushings sleeved o'n said' boltand rotatable in thevopenings in the inboard ends'of said'splice' bars, means associatedwith' said"ecc'entricbushings for `rotating them relative tosaid'boltand'splice bars totake up 4play in said' joint, a bolt'extending'through the registering openings in said outboardv spar andin the outboard ends of said splice bars, and spherical 'bushings'sleeved' 4'on'A said outboard boit and corresponding ywith thesphericalsu'rfaces in the ou'tboa'rd b olt receiving, openings in 'therespective splicebars.

8. An airplane wing spar joint construction comprising inboard andoutboard wing spars disposed in end to end relation, splice barsdisposed on opposite sides of said wing spars and spanning the adjacentends thereof, said adjacent ends of said wing spars having openingstherein and said splice bars having openings in the ends thereofregistering with the respective wing spar openings, the openings in theoutboard ends of said splice bars having spherical surfaces, a boltextending through the registering openings in said inboard wing spar andthe inboard ends of said splice bars, eccentric bushings sleeved on saidbolt and rotatable in the openings in the inboard ends of said splicebars, means associated with said eccentric bushings for rotating themrelative to said bolt and splice bars to take up play in said joint, abolt extending through the registering openings in said outboard sparand in the outboard ends of said splice bars, spherical bushings sleevedon said outboard bolt and cooperating with the spherical surfaces in theoutboard bolt receiving openings in the respective splice bars, and ashear pin having a body portion interposed between the opposed ends ofsaid Wing spars and outstanding end flanges disposed in abuttingrelation to the opposite side faces thereof.

9. An airplane wing spar joint construction comprising inboard andoutboard wing spars disposed in end to end relation, splice barsdisposed on opposite sides of said wing spars and spanning the adjacentends thereof, said adjacent ends of said wing spars having openingstherein and said splice bars having openings in the ends thereofregistering with the respective wing spar openings, the openings in theoutboard ends of said splice bars having spherical surfaces, a boltextending through the registering openings in said inboard Wing spar andthe inboard ends of said splice bars, eccentric bushings sleeved on saidbolt and rotatable in the openings in the inboard ends of the respectivesplice bars, a bolt extending through the registering openings in saidoutboard spar and in the outboard ends of said splice bars,

and spherical bushings sleeved on said outboard bolt and cooperatingwith the spherical surfaces in the outboard bolt receiving openings ofthe respective splice bars.

10. An airplane Wing spar joint construction d comprising inboard andoutboard wing spars disposed in end to end relation, splice barsdisposed on opposite sides of said wing spars and spanning the adjacentends thereof, said adjacent ends of said Wi'ng spars having openingstherein and said splice bars having openings in the ends thereofregistering with the respective Wing spar openings, the openings in theoutboard ends of said splice bars having spherical surfaces, a boltextending through the registering openings in said inboard Wing spar andthe inboard ends of said splice bars, eccentric bushings sleeved on saidbolt and rotatable in the openings in the inboard ends of said splicebars, said bushings having serrated outer end portions, arms havingserrated openings adapted to interlock with the serrated ends of therespective bushings, means for locking said arms to said splice bars, abolt extending through the registering openings in said outboard sparand in the out-board ends of said splice bars, spherical bushingssleeved on said outboard bolt and cooperating with the sperical surfacesin the outboard bolt receiving openings of the respective splice bars,and a shear pin having a body portion interposed between the opposedends of said Wing spars and outstanding end flanges disposed in abuttingrelation to the side faces thereof.

11. An airplane wing spar joint construction ,comprising inboard andoutboard wing spars disposed in end to end relation and separateconnections therebetween, each of said connections comprising spliceb-ars disposed on o-pposite sides of said Wing spars and spanning theadjacent ends thereof, said adjacent ends of said wing spars having.Openings therein and said splice bars having openings in the endsthereof registering with the respective Wing spar openings, theo-penings in the outboard ends of said splice bars having sphericalsurfaces, a bolt extending through the registering openings in saidinboard wing spar and the inboard ends of said splice bars, eccentricbushings sleeved on said rbolt and rotatable in the openings in theinboard ends of said splice bars, nuts on the outer ends of said boltfor clamping said bushings to said splice bars and the latter to saidspars, arms fixed to said eccentric bushings for rotating the same insaid splice bars and relative to said bolt, means for angularlyadjusting said arms relative to said bushings, means for locking saidarms to said splice bars, a bolt extending through the registeringopenings in said outboard spar and in the outboard ends of said splicebars, spherical bushings sleeved on said outboard bolt and cooperatingwith the sperical surfaces in the outboard bolt receiving openings ofsaid splice bars, nuts on the outer ends of said outboard bolt forclamping said spherical bushings to said splice bars and the latter tosaid spars, and a shear pin having a body portion interposed between theopposed ends of said Wing spars substantially in the plane of theinboard and outboard bolts of one of said separate spar connections andoutstanding end anges disposed in abutting relation to the opposite sidefaces of said spars. Y

12. An airfoil spar joint construction comprising two spars disposed inend to end relation and having opposed transverse grooves in theiradjacent ends, splice bars disposed on opposite sides of said spars andextending across the adjacent ends thereof and the en'ds of the opposedgrooves therein, separate connections between said splice 'bars and therespective spars, one of said connections including means fcraccommodating misalinement of said spars and the other of saidconnections including means for separately adjusting each of said splicebars relative to said spars to take up end play in said spar joint andto tension said splice bars, and a shear pin seated in said opposedgrooves in said ends of said spars.

ALBERT UTSCH.

REFERENCES CITED The following references are of record in the ille ofthis patent:

UNITED STATES PATENTS Number Name Date 1,941,348 Hathorn Dec. 26, 1933`1,097,185 Oehrle May 19, 1914 1,704,989 Grauel Mar. 12, 1929 132,287Hooker Oct. 15, 1872 2,097,324 Hill Oct. 26, 1937

